Cod sursa(job #2629018)
Utilizator | Manea Dorin dorinm17 | Data | 18 iunie 2020 16:41:20 |
---|---|---|---|
Problema | Fractii | Scor | 30 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva de probleme | Marime | 0.49 kb |
#include <iostream>
#include <fstream>
using namespace std;
const int DIM=1000000;
int F[DIM+1];
int main()
{
ifstream f("fractii.in");
ofstream g("fractii.out");
int n, i, j, s=0;
f>>n;
for(i=1 ; i<=n ; i++)
F[i]=i;
for(i=2; i<=n; i++)
if(F[i]==i)
{
F[i]--;
for(j=2 ; j*i<=DIM; j++)
F[j*i]= F[j*i]/i * (i-1);
}
for(i=1; i<=n; i++)
s+=F[i];
g<<s*2-1<<endl;
}